1. Field of the Invention
The present invention relates to a cargo door that is utilized additionally as a ramp.
2. Description of the Related Art
Effective use of a door as a ramp that folds from the back of a transport device and utilizes struts and/or cables for support is known in the art. Even doors having multiple folds therein are utilized to provide a ramp surface into a storage or transporting container. Door/ramp combinations that are strong enough to hold the weight of vehicles are typically themselves rather heavy requiring supports underneath and/or cables to assist in the closing of the door/ramp. In lightweight trailers, such as those that carry mowers, the weight of the ramp is reduced by utilizing a permeable ramp allowing not only a reduction in material to thereby reduce weight, but also allowing air to travel therethrough to lower the aerodynamic drag on such a trailer.
The cargo system, which is defined as that which a commercial carrier would utilize to transport loads over some distance, requires a method of unloading. Many cargo transports, such as semi-tractor trailers utilize loading docks at the cargo pickup and delivery points. In those instances, a ramp or other unloading device is not necessary because of the elevated nature of the loading dock. When delivering or picking up from smaller businesses and for individuals, a loading dock is often not available. As such, lift gates are often attached to the back of a vehicle to allow the unloading of heavy cargo. A lift gate is normally a hydraulically operated mechanism that is powered from the electrical system of the vehicle to elevate and/or lower cargo onto the ground. Other solutions include ramps that are stored beneath the truck body which are slid out and then connected to the tail end of the truck, thereby allowing a ramped surface for the loading and unloading of cargo.
What is needed in the art is a door/ramp that can be lowered without the necessity of cables, struts, or hydraulics to counterbalance the weight of the door.